The disclosed technology relates to structurant polymers based on polyurethane/polyurea chemistry, which efficiently thicken or gel (i.e., provide structure to) oils and oil mixtures. The disclosed technology further relates to structurant polymers based on polyurethane/polyurea chemistry that are oil soluble or oil dispersible and that provide beneficial properties, such as, for example, desirable clarity and/or feel. In addition, the technology relates to cosmetically and/or household acceptable formulations containing an oil as well as a structurant polymer based on polyurethane/polyurea chemistry.
In the personal care industry, organic phase materials, i.e., oils, emollients, fragrances etc., are used in lotions, crémes and other products to replenish the oils lost from a substrate, such as skin or hair, during cleansing in order to keep the substrate hydrated, and to improve visual appearance and sensory perception. Most oils and emollients used in the personal care industry are low viscosity fluids which, if used alone, are difficult to handle due to their low viscosity and low surface tension. In addition, various combinations of oils and emollients are often used to provide a pleasant sensory experience that would be otherwise difficult to obtain from single or simple mixture of oils/emollients due to the heavy or tacky feeling of many of the oils and emollients.
A good deal of effort has been dedicated to the development of thickeners and sensory modifiers for such oil systems but there are large gaps in the current technologies. For example, with respect to thickening of oils, US 2010/0190648, published Jul. 29, 2010 to Croda International, teaches a structured oil system of an oil and a structurant oligomer including urethane and/or urea linkages. The structurant oligomer is limited to those derived from dimer or trimer fatty acids.
However, oils and emollients, and even fragrances used in the personal care industry span the range of polarities. Current oil thickeners on the market work very well with low polarity oils such as isohexadecane and mineral oil or with very polar oils and solvents, but there are fewer that work with medium polar oils and emollients or span a large range of oil polarities. In addition, it is much more difficult finding thickener systems that work across oil types and mixtures and leave a highly clear system. The availability of one thickener system would not address the varying oil types.
In addition, characterization of the polarity of oils, emollients and fragrances is a difficult process since many of those used are not a single molecule but, especially in natural oils, are mixtures of molecules with various but similar structures, which may contain polar groups not found in the main chemical species. Depending on the thickening mechanism, these lower concentration species can have a pronounced effect on the thickening ability of a thickener.
There are several different mechanisms by which liquids can be thickened: these include hydrodynamic volume, microgels, fibrils and associative molecules or combinations of these. The challenge in commercial formulations is to find materials that will thicken or gel the liquid in the most efficient and lowest cost manner. In all cases, the material used to thicken or gel the oil should be easily soluble or dispersible in the oil. Since oils possess a wide range of polarities, it is difficult to find a single system that will work for all oils. Furthermore, the rheological response that one needs or wants must be factored in the selection of the mechanism since interactions can lead to unpleasant results. Current commercial oil thickeners and gellants use a variety of chemistries which result in a complex understanding of where certain technologies can and cannot be used.
Accordingly, there is a need for new solutions to the problem of thickening formulations containing an organic phase.